test: use getmempoolentry instead of getrawmempool in functional tests when appropriate

test/functional/mempool_unbroadcast.py

@@ -94,9 +94,7 @@ class MempoolUnbroadcastTest(BitcoinTestFramework):
 
         self.log.info("Rebroadcast transaction and ensure it is not added to unbroadcast set when already in mempool")
         rpc_tx_hsh = node.sendrawtransaction(txFS["hex"])
-        mempool = node.getrawmempool(True)
-        assert rpc_tx_hsh in mempool
-        assert not mempool[rpc_tx_hsh]['unbroadcast']
+        assert not node.getmempoolentry(rpc_tx_hsh)['unbroadcast']
 
     def test_txn_removal(self):
         self.log.info("Test that transactions removed from mempool are removed from unbroadcast set")